EAU 2017: Controversies: What helps more to characterize the disease? Imaging

London, England (UroToday.com) As part of this morning’s EAU 2017 “Prostate Cancer Imaging” session, Dr. Tobias Maurer presented a high-level talk discussing imaging for characterizing prostate cancer. Dr. Maurer highlighted that for primary staging of prostate cancer, imaging generally does a good job delineating stage and may be used for deciding the extent of local treatment and whether a patient should be considering for primary systemic therapy prior to localized treatment. Specifically, for assessing primary T-stage, Dr. Maurer advocates for use of MRI. For patients with cT2 disease, MRI has a specificity of 88-97% for detecting extracapsular extension and/or seminal vesicle invasion, which may guide a surgeon as to the degree of nerve sparing to perform during radical prostatectomy. Certainly, there has been excitement at EAU 2017 regarding PSMA-PET imaging, however in the primary staging setting Dr. Maurer cautions that while PSMA-PET may improve staging, the clinical relevance at this point is still to be determined. For detection of nodal disease and bone/visceral metastases, PSMA-PET has outperformed CT/MRI and bone-scan in recent small studies.

A second advantage of imaging for characterizing prostate cancer is when staging recurrent prostate cancer, specifically defining whether disease is localized, loco-regional or distant metastases. In a recent meta-analysis [1], PSMA-PET was able to detect recurrent disease in 56% of patients at a PSA of 0.5 ng/mL, whereas at a PSA of 1.0 ng/mL detection rates are 70%. Although PSA is more sensitive for detecting recurrence, the advantage of PSMA-PET is that it provides localization of recurrent disease

Third, imaging allows characterization of treatment response in the metastatic setting and whether it is reasonable to discontinue systemic treatment in patients with excellent response. Particularly for patients with metastatic castration-resistant prostate cancer (mCRPC) treated with docetaxel, early work from Dr. Maurer’s group suggests that PSMA-PET is able to assess degree of disease burden following chemotherapy.

In summary, prostate imaging continues to improve, particularly with PSMA-PET, however Dr. Maurer cautions that current imaging modalities are expensive and not as sensitive as biomarkers for detecting recurrence. As Dr. Maurer eloquently noted in his first slide, when discussing biomarkers vs imaging for characterizing disease, the answer is not necessarily one or the other, but where/when to use each modality.

1. Perera M, Papa N, Christidis D, et al. Sensitivity, specificity, and predictors of Postitive 68Ga-Prostate-specific Membrane Antigen Positron Emission Tomography in Advanced Prostate Cancer: A Systematic Review and Meta-analysis. Eur Urol 2016;70(6):926-937.

Presented by: Tobias Maurer, Technische Universitat Munchen, Munich, Germany

Written by: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto
Twitter: @zklaassen_md

at the #EAU17 -March 24-28, 2017- London, England

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